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Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 16.0	$ 14.7	$ 12.9
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	1.7	1.0	0.5
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 14.3
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	9 years 18 months
Employee Service Share-based Compensation, Cash Flow Effect, Cash Used to Settle Awards	$ 5.7	3.7	2.9
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 13.9	$ 9.3	$ 7.6
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0	0	0
Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period	0	0	0
Exercise of stock options, Shares	918
Minimum [Member] | Risk Free Rate [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Requisite service period			3 months
Minimum [Member] | Volatility [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Requisite service period			1 year
Maximum [Member] | Risk Free Rate [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Requisite service period			3 years
Maximum [Member] | Volatility [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Requisite service period			3 years
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 100.53	$ 72.98	$ 71.85
Requisite service period	3 years	3 years	3 years
Restricted Stock | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	5 years
Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 1.0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	4 years 2 months 12 days
Exercise of stock options, Shares	918	69,852	17,823
Proceeds from Stock Options Exercised	$ 0.1	$ 2.9	$ 0.9
Employee Stock Option [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 months 18 days
Employee Stock Option [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years 3 months 18 days
2013 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	2,000,000

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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